Harlem Rep. Charles Rangel has received a much needed transfusion in the fight of his political life: the endorsement of the 220,000-member health-care workers’ union SEIU Local 1199.

The backing of the city’s largest union could help stop the momentum of state Sen. Adriano Espaillat heading into the June 24 Democratic congressional primary.

Rangel, 83, has seen a significant segment of the Democratic and labor establishment abandon him for Espaillat, including City Council Speaker Melissa Mark-Viverito, Bronx Borough President Ruben Diaz Jr. and unions representing teachers, hotel and retail workers.

But 1199 President George ­Gresham said Rangel has a lengthy rec­ord of accomplishments that ­entitle him to another term.

“[Rangel] has been a steady and consistent fighter for quality health care, immigrant rights, affordable housing, public education and good jobs for more than 40 years,” said Gresham.

Rangel defeated Espaillat only by about 1,000 votes two years ago and some politicos now believe the race is ­Espalliat’s to lose.

Rangel said he would retire at the end his 23rd term in 2016, should he be re-elected.